1.6.3Additional lessons
Ecosystem Loss — IB Biology SL Revision Notes & Topical Questions
5 min read 4 parts Lesson 8 of 142
Curriculum Equation Key قوانين الرقم الهيدروجيني والاتزان الأيوني - pH & Acid-Base Equilibrium FormulasFast Exam Solution
pH = -log[H⁺] | pOH = -log[OH⁻] | pH + pOH = 14 | [H⁺][OH⁻] = 10⁻¹⁴
Word Equation & Conditions: الرقم الهيدروجيني = -لوغاريتم تركيز أيون الهيدروجين | pH + pOH = 14
Location & Specifications: الاتزان الأيوني، كيمياء 3 ثانوي، التحصيلي، و AP Chemistry.
Part 1 of 4What Ecosystem Loss Means
Ecosystem
- Ecosystem A community of organisms interacting with each other and with the physical environment in a particular area.
Ecosystem loss
- Ecosystem loss The destruction, degradation or conversion of an ecosystem so that its original community of species can no longer persist.
Direct loss
- Direct loss Habitat is cleared completely, for example when forest is felled and replaced by crops or buildings.
Fragmentation
- Fragmentation Roads and fields split a habitat into small isolated patches that support fewer species and smaller populations.
Knock-on effects
- Knock-on effects Losing one ecosystem reduces ecosystem services such as water regulation, carbon storage and soil protection.
Scale
- Scale Large areas can be lost slowly through many small changes, so satellite images and repeated surveys are used to track the change.
Part 2 of 4Causes of Ecosystem Loss
Most ecosystem loss is anthropogenic.
Causes of Ecosystem Loss
Deforestation
- Deforestation Forests are cleared for timber, farmland and plantations, removing trees and the many species that depend on them.
Agriculture
- Agriculture Conversion to monoculture crops replaces diverse communities, and drainage of wetlands eliminates their specialised species.
Urbanisation
- Urbanisation Towns and roads cover natural habitat and fragment what remains into small, isolated patches.
Pollution and warming
- Pollution and warming Nutrient runoff, plastics and rising temperatures degrade ecosystems such as coral reefs and mangroves.
| Cause | Ecosystem affected | Typical consequence |
|---|---|---|
| Logging and clearing | Tropical forest | Loss of canopy species, soil erosion and stored carbon |
| Drainage for farmland | Wetlands | Loss of specialised plants, birds and water filtering |
| Rising sea temperature | Coral reef | Bleaching and collapse of the reef community |
Part 3 of 4Case Studies of Ecosystem Loss
1
Mixed dipterocarp forests in Southeast Asia have been logged for valuable timber and cleared for plantations such as oil palm.
2
Loss of canopy trees removes food and nesting sites, so animals that depend on the forest, including orangutans, decline.
3
Great Barrier Reef: rising sea temperatures cause coral bleaching, and farm runoff adds nutrients that harm reef communities.
4
Mangrove forests in many regions have been cleared for aquaculture and coastal building, removing nursery habitat and coastal protection.
5
For any case study, state the cause, the evidence of change, and the consequence for species and ecosystem services.
Part 4 of 4Exam Checklist & Tips
1.6.3 – Key Points for the Exam
- Habitat fragmentation Division of a habitat into smaller, isolated patches.
- Ecosystem services Benefits that ecosystems provide to people, such as clean water, flood control and pollination.
- Monoculture Growing a single crop species over a large area.
- Coral bleaching Loss of symbiotic algae from corals under stress, leaving them white and vulnerable.
Common Mistakes
- Describing the loss of an ecosystem as only the loss of species, ignoring lost processes such as nutrient cycling.
- Treating fragmentation as harmless because some habitat remains; small patches support fewer species.
- Giving a case study without evidence, for example data on area cleared or reef cover.
- Mixing up cause and consequence, such as saying bleaching causes warming.
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